In a quiet cul-de-sac in London's exclusive Kensington area, there's an imposing Victorian town house that has an air of the Empire about it, even though its owners do not. The house  which has eight bedrooms and six bathrooms spread over six floors, an elevator and a garden  belongs to a Swiss family who, according to Tom Tangney, estate agent for realtor Knight Frank, make their money in finance. Tired of paying the upkeep on a place they hardly use, they've put it on the market for $18.5 million. And at that price, "I expect the buyer...